"""
Description:
Your task is to create a function that does four basic mathematical operations.

The function should take three arguments - operation(string/char), value1(number), value2(number).
The function should return result of numbers after applying the chosen operation.

Examples:
    basic_op('+', 4, 7)         # Output: 11
    basic_op('-', 15, 18)       # Output: -3
    basic_op('*', 5, 5)         # Output: 25
    basic_op('/', 49, 7)        # Output: 7
"""


def basic_op(operator, value1, value2):
    result = None
    if operator == "+":
        result = value1 + value2
    elif operator == "-":
        result = value1 - value2
    elif operator == "*":
        result = value1 * value2
    elif operator == "/":
        result = value1 / value2
    return result
