human
I wrote the below code

    ignore_nonexistent_tables = kw.pop('ignore_nonexistent_tables', False)
    only_synonyms = kw.pop('only_synonyms', False)
    columns = util.ordered_column_set(columns)
    omit = util.column_set()
    for col in columns:
        for fk in chain(*[c.foreign_keys for c in col.proxy_set]):
            for c in columns:
                if (c is col):
                    continue
                try:
                    fk_col = fk.column
                except exc.NoReferencedColumnError:
                    if ignore_nonexistent_tables:
                        continue
                    else:
                        raise
                except exc.NoReferencedTableError:
                    if ignore_nonexistent_tables:
                        continue
                    else:
                        raise
                if (fk_col.shares_lineage(c) and ((not only_synonyms) or (c.name == col.name))):
                    omit.add(col)
                    break
    if clauses:
        def visit_binary(binary):
            if (binary.operator == operators.eq):
                cols = util.column_set(chain(*[c.proxy_set for c in columns.difference(omit)]))
                if ((binary.left in cols) and (binary.right in cols)):
                    for c in reversed(columns):
                        if (c.shares_lineage(binary.right) and ((not only_synonyms) or (c.name == binary.left.name))):
                            omit.add(c)
                            break
        for clause in clauses:
            if (clause is not None):
                visitors.traverse(clause, {}, {'binary': visit_binary})
    return ColumnSet(columns.difference(omit))

What's a good function header?

Here's a good function header?
assistant
#Here's a good function header.

def reduce_columns(columns, *clauses, **kw):