Set up neccessary environment variables

    This appends all path of sys.path to the python path
    so mayapy will find all installed modules.
    We have to make sure, that we use maya libs instead of
    libs of the virtual env. So we insert all the libs for mayapy
    first.

    :returns: None
    :rtype: None
    :raises: None

def setup_environment():
    """Set up neccessary environment variables

    This appends all path of sys.path to the python path
    so mayapy will find all installed modules.
    We have to make sure, that we use maya libs instead of
    libs of the virtual env. So we insert all the libs for mayapy
    first.

    :returns: None
    :rtype: None
    :raises: None
    """
    osinter = ostool.get_interface()
    pypath = osinter.get_maya_envpath()
    for p in sys.path:
        pypath = os.pathsep.join((pypath, p))
    os.environ['PYTHONPATH'] = pypath