(base) bash-5.2$ date
Wed Nov  8 02:33:51 PM EST 2023
(base) bash-5.2$ pwd
/home/accts/sbs5/cs200/www/lectures
(base) bash-5.2$ p
Python 3.11.6 (main, Oct  3 2023, 00:00:00) [GCC 12.3.1 20230508 (Red Hat 12.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import this
The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!
>>> def f2():
...   return a
... 
>>> f2()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in f2
NameError: name 'a' is not defined
>>> a = 2
>>> f2()
2
>>> a = [1,2]
>>> a
[1, 2]
>>> a[2]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: list index out of range
>>> x = 0
def f13():
    x += 1
    return x
>>> ... ... ... 
>>> f13()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in f13
UnboundLocalError: cannot access local variable 'x' where it is not associated with a value
>>> def ff():
...   x+= 1
...   return x
... 
>>> ff()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in ff
UnboundLocalError: cannot access local variable 'x' where it is not associated with a value
>>> def fff():
...   return x
... 
>>> fff()
0
>>> import dis
>>> dir(dis)
['BINARY_OP', 'Bytecode', 'CACHE', 'COMPILER_FLAG_NAMES', 'EXTENDED_ARG', 'FORMAT_VALUE', 'FORMAT_VALUE_CONVERTERS', 'HAVE_ARGUMENT', 'Instruction', 'JUMP_BACKWARD', 'LOAD_CONST', 'LOAD_GLOBAL', 'MAKE_FUNCTION', 'MAKE_FUNCTION_FLAGS', 'Positions', 'UNKNOWN', '_ExceptionTableEntry', '_INT_BITS', '_INT_OVERFLOW', '_Instruction', '_OPARG_WIDTH', '_OPNAME_WIDTH', '_Unknown', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', '_all_opmap', '_all_opname', '_cache_format', '_deoptop', '_disassemble_bytes', '_disassemble_recursive', '_disassemble_str', '_empty_slot', '_find_imports', '_find_store_names', '_format_code_info', '_get_code_array', '_get_code_object', '_get_const_info', '_get_const_value', '_get_instructions_bytes', '_get_name_info', '_have_code', '_inline_cache_entries', '_is_backward_jump', '_nb_ops', '_parse_exception_table', '_parse_varint', '_specializations', '_specialized_instructions', '_test', '_try_compile', '_unpack_opargs', 'cmp_op', 'code_info', 'collections', 'deoptmap', 'dis', 'disassemble', 'disco', 'distb', 'findlabels', 'findlinestarts', 'get_instructions', 'hascompare', 'hasconst', 'hasfree', 'hasjabs', 'hasjrel', 'haslocal', 'hasname', 'hasnargs', 'io', 'opmap', 'opname', 'pretty_flags', 'show_code', 'spec_op', 'specialized', 'stack_effect', 'sys', 'types']
>>> dis.code_info(f13)
'Name:              f13\nFilename:          <stdin>\nArgument count:    0\nPositional-only arguments: 0\nKw-only arguments: 0\nNumber of locals:  1\nStack size:        2\nFlags:             OPTIMIZED, NEWLOCALS\nConstants:\n   0: None\n   1: 1\nVariable names:\n   0: x'
>>> f13
<function f13 at 0x7f1a28674360>
>>> print (dis.code_info(f13))
Name:              f13
Filename:          <stdin>
Argument count:    0
Positional-only arguments: 0
Kw-only arguments: 0
Number of locals:  1
Stack size:        2
Flags:             OPTIMIZED, NEWLOCALS
Constants:
   0: None
   1: 1
Variable names:
   0: x
>>> print (dis.code_info(f))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'f' is not defined. Did you mean: 'f2'?
>>> print (dis.code_info(f2))
Name:              f2
Filename:          <stdin>
Argument count:    0
Positional-only arguments: 0
Kw-only arguments: 0
Number of locals:  0
Stack size:        1
Flags:             OPTIMIZED, NEWLOCALS
Constants:
   0: None
Names:
   0: a
>>> dis.dis(f13)
  1           0 RESUME                   0

  2           2 LOAD_FAST                0 (x)
              4 LOAD_CONST               1 (1)
              6 BINARY_OP               13 (+=)
             10 STORE_FAST               0 (x)

  3          12 LOAD_FAST                0 (x)
             14 RETURN_VALUE
>>> def s3e():
    a = 6
    b = 3
    return (a / b)
... ... ... ... 
>>> s3e()
2.0
>>> dis.dis(s3e)
  1           0 RESUME                   0

  2           2 LOAD_CONST               1 (6)
              4 STORE_FAST               0 (a)

  3           6 LOAD_CONST               2 (3)
              8 STORE_FAST               1 (b)

  4          10 LOAD_FAST                0 (a)
             12 LOAD_FAST                1 (b)
             14 BINARY_OP               11 (/)
             18 RETURN_VALUE
>>> def y():
a = 7
if a % 2:
return 1 + 3*a
else:
return a / 2
...   File "<stdin>", line 2
    a = 7
    ^
IndentationError: expected an indented block after function definition on line 1
>>> ...   File "<stdin>", line 2
    return 1 + 3*a
    ^
IndentationError: expected an indented block after 'if' statement on line 1
>>>   File "<stdin>", line 1
    else:
    ^^^^
SyntaxError: invalid syntax
>>>   File "<stdin>", line 1
SyntaxError: 'return' outside function
>>> 
>>> def y():
...   a = 7
...   if a%2:
...     return 1 + 3*a
...   else:
...     return a / 2
... 
>>> dis.dis(y)
  1           0 RESUME                   0

  2           2 LOAD_CONST               1 (7)
              4 STORE_FAST               0 (a)

  3           6 LOAD_FAST                0 (a)
              8 LOAD_CONST               2 (2)
             10 BINARY_OP                6 (%)
             14 POP_JUMP_FORWARD_IF_FALSE     8 (to 32)

  4          16 LOAD_CONST               3 (1)
             18 LOAD_CONST               4 (3)
             20 LOAD_FAST                0 (a)
             22 BINARY_OP                5 (*)
             26 BINARY_OP                0 (+)
             30 RETURN_VALUE

  6     >>   32 LOAD_FAST                0 (a)
             34 LOAD_CONST               2 (2)
             36 BINARY_OP               11 (/)
             40 RETURN_VALUE
>>> def x ():
...   return [n for n in range(10)]
... 
>>> x()
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> dis.dis(x)
  1           0 RESUME                   0

  2           2 LOAD_CONST               1 (<code object <listcomp> at 0x7f1a284c30f0, file "<stdin>", line 2>)
              4 MAKE_FUNCTION            0
              6 LOAD_GLOBAL              1 (NULL + range)
             18 LOAD_CONST               2 (10)
             20 PRECALL                  1
             24 CALL                     1
             34 GET_ITER
             36 PRECALL                  0
             40 CALL                     0
             50 RETURN_VALUE

Disassembly of <code object <listcomp> at 0x7f1a284c30f0, file "<stdin>", line 2>:
  2           0 RESUME                   0
              2 BUILD_LIST               0
              4 LOAD_FAST                0 (.0)
        >>    6 FOR_ITER                 4 (to 16)
              8 STORE_FAST               1 (n)
             10 LOAD_FAST                1 (n)
             12 LIST_APPEND              2
             14 JUMP_BACKWARD            5 (to 6)
        >>   16 RETURN_VALUE
>>> 
(base) bash-5.2$ pwd
/home/accts/sbs5/cs200/www/lectures
(base) bash-5.2$ tr -sc a-zA-Z '\n' < ../UNIX.html | head

html
head
LINK
href
http
zoo
cs
yale
edu
(base) bash-5.2$ head ../UNIX.html 
<html>
<head>
<LINK href="http://zoo.cs.yale.edu/classes/cs201/style.css" 
      rel="stylesheet" type="text/css">

<title>UNIX for CS 200/201 - Fall 2023.</title>
</head>

<h1>UNIX for CS 200/201 - Fall 2023.</h1>

(base) bash-5.2$ tr -sc a-zA-Z '\n' < ../UNIX.html | sort | head

a
a
a
a
a
a
a
a
a
(base) bash-5.2$ tr -sc a-zA-Z '\n' < ../UNIX.html | sort | uniq | head

a
A
about
above
abrt
ABRT
access
accessed
accts
(base) bash-5.2$ tr -sc a-zA-Z '\n' < ../UNIX.html | sort | uniq -c | head
      1 
    138 a
      9 A
      5 about
      3 above
      4 abrt
      1 ABRT
      6 access
      2 accessed
     18 accts
(base) bash-5.2$ pwd
/home/accts/sbs5/cs200/www/lectures
(base) bash-5.2$ p
Python 3.11.6 (main, Oct  3 2023, 00:00:00) [GCC 12.3.1 20230508 (Red Hat 12.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> def do_twice(func):
    ''' Decorator that executes a function twice and returns the results as a 2-tuple'''
    @wraps(func)
    def g(*args):
        val1 = func(*args)
        val2 = func(*args)
        return (val1, val2)
    return g
... ... ... ... ... ... ... ... 
>>> @do_twice
def add2(n):
    ''' add 2 to the input'''
    return n+2
... ... ... ... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in do_twice
NameError: name 'wraps' is not defined
>>> from functools import wraps
>>> @do_twice
def add2(n):
    ''' add 2 to the input'''
    return n+2
... ... ... ... 
>>> add2(4)
(6, 6)
>>> import random
def roll_dice():
    ''' roll a fair die - a random value between 1 and 6 inclusive.'''
    return random.randint(1,6)
>>> ... ... ... 
>>> roll_dice()
6
>>> roll_dice()
6
>>> roll_dice()
6
>>> roll_dice()
4
>>> roll_dice()
2
>>> roll_dice()
2
>>> roll_dice()
2
>>> roll_dice()
1
>>> roll_dice()
6
>>> roll_dice()
4
>>> @do_twice
def roll_dice():
    ''' roll a fair die - a random value between 1 and 6 inclusive.'''
    return random.randint(1,6)
... ... ... ... 
>>> roll_dice()
(6, 3)
>>> roll_dice()
(5, 2)
>>> roll_dice()
(1, 3)
>>> roll_dice()
(5, 2)
>>> def roll_sixes():
   number = random.randint(1,6)
   if number != 6:
     raise ValueError(number)
   return number
... ... ... ... ... 
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 1
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 4
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 5
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 2
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 4
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 1
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 4
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 1
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 3
>>> roll_sixes()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in roll_sixes
ValueError: 2
>>> roll_sixes()
6
>>> from retry import *
>>> roll_sixes()
Retrying (4)
Retrying (1)
Retrying (1)
Retrying (3)
Retrying (5)
Retrying (2)
6
>>> roll_sixes()
Retrying (1)
Retrying (4)
6
>>> roll_sixes()
Retrying (4)
Retrying (2)
Retrying (2)
Retrying (5)
Retrying (5)
6
>>> roll_sixes()
6
>>> d={}
>>> d[(1,2)] = 7
>>> d
{(1, 2): 7}
>>> d[(2,1)] = 9
>>> d
{(1, 2): 7, (2, 1): 9}
>>> 
(base) bash-5.2$ exit

Process shell finished