def check_input(letter: str) -> bool:
    """
    Author: Jeremy Trendoff

    Returns the validity of an input. 
    Takes a str parameter representing the input.

    >>> check_input('t')
    True

    >>> check_input('z')
    False
    """

    # A list representing the valid inputs
    vaild_inputs = ['2', '3', 'x', 'X', 't', 'T', 'p', 'P', 'e', 'E',
                    'i', 'I', 'v', 'V', 'h', 'H', 'l', 'L', 's', 'S', 'q', 'Q', 'd', 'D']

    # Checks if the input is valid and returns
    if letter in vaild_inputs:
        return True
    else:
        print('No such command!')
        return False