def get_timedelta_unit(delta):
    """
    Get the unit character from a numpy timedelta.
    
    Parameters
    ----------
    delta : np.timedelta64
        numpy timedelta
    
    Returns
    -------
    str
        the character for the timedelta unit
    
    Examples
    --------
    
    .. doctest:: podpac.core.coordinates.utils

        >>> get_timedelta_unit(np.timedelta64(1, 'D'))
        'D'
    
    Raises
    ------
    TypeError
        Description
    
    """
    try:
        dname = delta.dtype.name
    except AttributeError:
        raise TypeError("Cannot get timedelta unit from type '%s'" % type(
            delta))
    if not dname.startswith('timedelta'):
        raise TypeError("Cannot get timedelta unit from dtype '%s'" % dname)
    return dname[12:-1]
