Example Function Structure
All functions should have a triple-quoted comment directly under the
def line. This comment should describe:
- 
what the function does 
- 
what each parameter is and its type 
- 
what the function returns 
Here are two examples of well-defined functions:
def letter_count(letter,text):
    """
    This function counts the number of occurrences of a given letter in
    a given text.
      param letter: the letter to search for (type: a single char string)
      param text: the text to search in (type: string)
      returns: the number of times the letter occurrs in text (type: int)
    """
    count = 0
    for i in range(len(text)):
        if text[i] == letter:
            count = count + 1
    return count
def print_rules():
    """
    Prints the rules of the game to the screen.
      params:  None
      returns: None
    """
    print("Welcome to the game of life!")
    print("Here are the rules: ")
    print("Rule #1: be nice to others")
    print("Rule #2: don't give up")
    print("Rule #3: do your best")