def METHOD_NAME(spec, c1, c2):
    """Returns total number of counts in a spectrum between two channels"""
    if c1 > c2:
        raise ValueError("c1 must be less than c2")
    if c1 < 0:
        raise ValueError("c1 must be positive number above 0")
    if c2 > max(spec.channels):
        raise ValueError("c2 must be less than max number of channels")
    gc = sum(spec.counts[c1:c2])
    return gc