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(base) MAC:Fri Aug 20:07:57:~> python
Python 3.8.5 (default, Sep  4 2020, 02:22:02) 
[Clang 10.0.0 ] :: Anaconda, Inc. on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 2 + 2
4
>>> 2 - 2
0
>>> 2*2
4
>>> 10 / 3
3.3333333333333335
>>> 10 // 3
3
>>> 10 % 3
1
>>> 2**5
32
>>> type(2)
<class 'int'>
>>> 2**1000
10715086071862673209484250490600018105614048117055336074437503883703510511249361224931983788156958581275946729175531468251871452856923140435984577574698574803934567774824230985421074605062371141877954182153046474983581941267398767559165543946077062914571196477686542167660429831652624386837205668069376
>>> 3^4
7
>>> type(3.3333333333333335)
<class 'float'>
>>> #  floats are IEEE double precision floating point numbers
>>> .1 + .1 + .1 == .3
False
>>> .1 +.1 + .1
0.30000000000000004
>>> 4e5
400000.0
>>> 4E5
400000.0
>>> 4 + .5
4.5
>>> int(4.5)
4
>>> int(-4.5)
-4
>>> ## cast float to int results in truncation of decimal part
>>> float(4)
4.0
>>> z = complex(3,4)
>>> z
(3+4j)
>>> z**2
(-7+24j)
>>> # variable name rule
>>> # must start wiht alpha character or _
>>> # succeeding characters are alphanumeric or _
>>> number_of_snakes = 42
>>> type(number_of_snakes)
<class 'int'>
>>> number_of_snakes = "caterwaul"
>>> type(number_of_snakes)
<class 'str'>
>>> 4 < 5
True
>>> 5 < 4
False
>>> type(True)
<class 'bool'>
>>> 4 == 5  
False
>>> ## isequalto operator. It is distinct from = which is assignment.
>>> 5 = x
  File "<stdin>", line 1
SyntaxError: cannot assign to literal
>>> 4 <= 5
True
>>> 4 >-
  File "<stdin>", line 1
    4 >-
       ^
SyntaxError: invalid syntax
>>> 4 >= 5
False
>>> 4 != 5
True
>>> not(4 == 5)
True
>>> True or False
True
>>> True or True
True
>>> False or True
True
>>> False or False
False
>>> True and True
True
>>> True and False
False
>>> False and True
False
>>> False and False
False
>>> ## what is the order of operations?
>>> 
>>> x = "abcdefghijklmnopqrstuvwxyz"
>>> 
>>> x[1]
'b'
>>> x[0]
'a'
>>> type(x[1])
<class 'str'>
>>> x[1:4]
'bcd'
>>> x[1:4] + x[4:6]
'bcdef'
>>> # type determines context
>>> #  + adds numbers
>>> #  + concatenates sstrings
>>> "cows" + 42
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can only concatenate str (not "int") to str
>>> a = "cows"
>>> b = 42
>>> a + str(42)
'cows42'
>>> f"{a}{b}"
'cows42'
>>> x[1:6]
'bcdef'
>>> x[4:]
'efghijklmnopqrstuvwxyz'
>>> x[:4]
'abcd'
>>> x[::2]
'acegikmoqsuwy'
>>> x[::3]
'adgjmpsvy'
>>> x[1::3]
'behknqtwz'
>>> x[:13:3]
'adgjm'
>>> x.upper()
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> x
'abcdefghijklmnopqrstuvwxyz'
>>> y = x.upper()
>>> x
'abcdefghijklmnopqrstuvwxyz'
>>> y
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> y.lower()
'abcdefghijklmnopqrstuvwxyz'
>>> "#$%$EWDFSAvdrjgi[jer0fdsgerv23454332423".lower
<built-in method lower of str object at 0x7fe11016f3f0>
>>> "#$%$EWDFSAvdrjgi[jer0fdsgerv23454332423".lower()
'#$%$ewdfsavdrjgi[jer0fdsgerv23454332423'
>>> x
'abcdefghijklmnopqrstuvwxyz'
>>> q = x[0:x.find("m")] + x[x.find("m")]]
  File "<stdin>", line 1
    q = x[0:x.find("m")] + x[x.find("m")]]
                                         ^
SyntaxError: unmatched ']'
>>> q = x[0:x.find("m")] + x[x.find("m")]
>>> q
'abcdefghijklm'
>>> q = x[0:x.find("m")] + x[x.find("m":)]
  File "<stdin>", line 1
    q = x[0:x.find("m")] + x[x.find("m":)]
                                       ^
SyntaxError: invalid syntax
>>> q = x[0:x.find("m")] + x[x.find("m"):]
>>> q
'abcdefghijklmnopqrstuvwxyz'
>>> q = x[0:x.find("m")].upper() + x[x.find("m"):]
>>> q
'ABCDEFGHIJKLmnopqrstuvwxyz'
>>>