def dms2deg(x):
    """Transform *degrees:arcminutes:arcseconds* strings to degrees.

    Parameters
    ----------
    x : str
        The input angle written in the form, degrees:arcminutes:arcseconds

    Returns
    -------
    out : float
        The input angle as a number of degrees.

    """
    from astropy.coordinates import Angle
    ac = Angle(x, unit='degree')
    deg = float(ac.to_string(unit='degree', decimal=True))
    return deg
