Strings and user input

Strings are a bit like lists:

x = "hello"
print(x)
print(x[3])
print(x[1:3])
print(x + ' there')
print(len(x))
for c in x:
    print(c)

But you cannot modify a string like you modify a list, you have to copy it:

x = "hello"
x[3] = 'p'
y = x[:3] + 'p' + x[4:]
print(y)

The input function gets input from the user as a string:

# Ask the user for their name
name = input("What's your name? ")
print("Hello, " + name)

f-strings are very convenient:

# Ask the user for their name
name = input("What's your name? ")
print(f"Hello, {name}")

Problems

Write a program that prints each letter of a string and its index
Write a program that computes the length of a string (without using the len function, of course)
Write a program to ask the user for their full name and converts it into an email address. For example:
```
Enter your full name: Boaty McBoatface
Your email is boaty.mcboatface@takenolab.com
```
Write a program that counts the number of words in a string. For example:
```
Enter a string: The quick brown fox
The string has 4 words in it
```

Write a program that checks if a string is a number. For example:

Enter a string: 1234
The string is a number
Enter a string: 1234e
The string is not a number
Enter a string: f42kl
The string is not a number

Write a program that checks if a string is in snake case. For example:

Enter a string: a_python_variable
The string is in snake case
Enter a string: aPythonVariable
The string is not in snake case
Enter a string: aPython_variable
The string is not in snake case

Write a program that checks if a string is in camel case. For example:

Enter a string: a_python_variable
The string is not in camel case
Enter a string: aPythonVariable
The string is in camel case
Enter a string: aPython_variable
The string is not in camel case

Write a program that converts a string from snake case to camel case, and another program that converts a string from camel case to snake case.

Once you have completed the problems above, look at the Python documentation to see the inbuilt string functions: https://docs.python.org/3/library/stdtypes.html#str