import sys

REQUIRED_PYTHON = "python3"

def main():

    system_major = sys.version_info.major

    if REQUIRED_PYTHON == "python":

        required_major = 2

    elif REQUIRED_PYTHON == "python3":

        required_major = 3

    else:

        raise ValueError("Unrecognized python interpreter: {}".format(

            REQUIRED_PYTHON))

    if system_major != required_major:

        raise TypeError(

            "This project requires Python {}. Found: Python {}".format(

                required_major, sys.version))

    else:

        print(">>> Development environment passes all tests!")

if __name__ == '__main__':

    main()