def wset(exprs):
    '\n    Extract the working set out of a set of equations.\n    '
    return {i.function for i in flatten([e.free_symbols for e in as_tuple(exprs)]) if i.function.is_AbstractFunction}
Extract the working set out of a set of equations.
def wset(exprs):
    '\n    \n    '
    return {i.function for i in flatten([e.free_symbols for e in as_tuple(exprs)]) if i.function.is_AbstractFunction}