def prop_convert(prop):
    """Take property urls and converts them into more human readable names.

    Args:
        prop (str): a url for a property, e.g. http://purl.org/dc/terms/title
                    or http://sbols.org/v2#type

    Raises:
        ValueError: raised if the prop is not a string

    Returns:
        prop: the updated more human readable prop (may be unchanged depending
                on the original input)
    """
    if type(prop) is str:
        idx = prop.find('#')

        if idx >= 1:
            prop = prop[idx + 1:]
            prop = prop.title()

        if prop == 'Type':
            prop = 'Types'
        if prop == 'Sourceorganism':
            prop = 'Source Organism'
        if prop == 'Targetorganism':
            prop = 'Target Organism'
        if prop == 'Designnotes':
            prop = 'Design Notes'
        if prop == 'http://purl.org/dc/terms/title':
            prop = 'Part Name'
        if prop == 'http://purl.org/dc/terms/description':
            prop = 'Part Description'
        if prop == 'http://purl.obolibrary.org/obo/OBI_0001617':
            prop = 'OBI_0001617'

        return prop
    else:
        raise ValueError