>>> def f(x): return x*3
... 
>>> f(4)
12
>>> f = 14
>>> f(4)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable
>>> ## function names are variable names
>>> ## functions are objects on the heap.
>>> 5
5
>>> "cows"
'cows'
>>> (lambda x: 3*x + 1)(5)
16
>>> (lambda : print("fooment"))()
fooment
>>> (lambda x, y, z : x + 2*y + 3*z)(1,2,3)
14
>>> cat = lambda x, y, z : x + 2*y + 3*z
>>> cat(1,2,3)
14
>>> ^D
MAC:Thu Mar 03:12:56:~> vi table_of_values.py
MAC:Thu Mar 03:12:59:~> python table_of_values.py 
<tr><td>5</td><td>625</td></tr>
MAC:Thu Mar 03:12:59:~> !vi
vi table_of_values.py
MAC:Thu Mar 03:13:02:~> python table_of_values.py 
None
MAC:Thu Mar 03:13:02:~> !vi
vi table_of_values.py
MAC:Thu Mar 03:13:02:~> !p
python table_of_values.py 
<table>
<tr><th>x</th><th>f(x)</th></tr>
<tr><td>5</td><td>27</td></tr>
<tr><td>2</td><td>6</td></tr>
<tr><td>8</td><td>66</td></tr>
<tr><td>9</td><td>83</td></tr>
<tr><td>12</td><td>146</td></tr>
<tr><td>0</td><td>2</td></tr>
</table>
MAC:Thu Mar 03:13:02:~> !vi
vi table_of_values.py
>>> for k, item in enumerate(x):
...     print(f"x[{k}] = {x[k]}")
... 
x[0] = cat
x[1] = dawg
x[2] = elephant
x[3] = ferret
x[4] = goat
>>> for k in enumerate(x):
...     print(f"x[{k[0]}] = {k[1]}")
... 
x[0] = cat
x[1] = dawg
x[2] = elephant
x[3] = ferret
x[4] = goat
>>> for k, item in enumerate(x, 50):
...     print(k, item)
... 
50 cat
51 dawg
52 elephant
53 ferret
54 goat
>>> for k, item in enumerate("caterwaul"):
...     print(f"{k} {item}")
... 
0 c
1 a
2 t
3 e
4 r
5 w
6 a
7 u
8 l
>>> ^D
MAC:Thu Mar 03:13:14:loopy> python loopy.py
**************** Problem 1 tests **************
FAIL because f([[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], <function <lambda> at 0x103770e50>]) != [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]. Failed Output: []
**************** Problem 2 tests **************
**************** Problem 3 tests **************
FAIL because f([[0, 12, 4, 51, 3, 9, 40], 20]) != 91. Failed Output: 0
**************** Problem 4 tests **************
FAIL because f([1, 5, 7, 9, 11, 13, 21, 25]) != True. Failed Output: False
**************** Problem 5 tests **************
**************** Problem 6 tests **************
FAIL because f(['cat', 'elephant']) != cealtephant. Failed Output: 
**************** Problem 7 tests **************
FAIL because f([10, <function <lambda> at 0x103770ee0>]) != 385. Failed Output: 0
**************** Problem 8 tests **************
FAIL because f(50) != 12586269025. Failed Output: 0
0
MAC:Thu Mar 03:13:14:loopy> !vi
vi loopy.py
>>> for k, item in enumerate("cows"):
...     print(f"{3*k + 1} {item}")
... 
1 c
4 o
7 w
10 s
>>> x = [4,7,1,2,1]
>>> x = reversed(sorted(x))
>>> x
<list_reverseiterator object at 0x1050da3b0>
>>> list(x)
[7, 4, 2, 1, 1]
>>> x.sort(reverse=True)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'list_reverseiterator' object has no attribute 'sort'
>>> x = [4,7,1,2,1]
>>> x.sort(reverse=True)
>>> x
[7, 4, 2, 1, 1]
>>> x.sort()
>>> x
[1, 1, 2, 4, 7]
>>> x.sort(reverse=False)
>>> x
[1, 1, 2, 4, 7]
>>> x ="amanaplanacanalpanama"
>>> x.find("a")
0
>>> x.rfind("l")
14
>>> x
'amanaplanacanalpanama'
>>>