def METHOD_NAME(row, uri):
    if uri in terms:
        value = row.data[uri]
    elif uri == scientific_name_uri:
        # Assume the library has taken care of utf-8 issues for us
        value = canonical_name(row.data[canonical_name_uri])
    elif uri == taxon_id_uri:
        value = row.id
    else:
        print '** Field is required but missing:', uri
        value = ''
    return value