def symbols(names, **args):
    result = []

    if isinstance(names, string_types):
        marker = 0
        literals = ['\,', '\:', '\ ']
        for i in range(len(literals)):
            lit = literals.pop(0)
            if lit in names:
                while chr(marker) in names:
                    marker += 1
                lit_char = chr(marker)
                marker += 1
                names = names.replace(lit, lit_char)
                literals.append((lit_char, lit[1:]))
        def literal(s):
            if literals:
                for c, l in literals:
                    s = s.replace(c, l)
            return s

        names = names.strip()
        as_seq = names.endswith(',')
        if as_seq:
            names = names[:-1].rstrip()
        if not names:
            raise ValueError('no symbols given')

        # split on commas
        names = [n.strip() for n in names.split(',')]
        if not all(n for n in names):
            raise ValueError('missing symbol between commas')
        # split on spaces
        for i in range(len(names) - 1, -1, -1):
            names[i: i + 1] = names[i].split()

        cls = args.pop('cls', Symbol)
        seq = args.pop('seq', as_seq)

        for name in names:
            if not name:
                raise ValueError('missing symbol')

            if ':' not in name:
                symbol = cls(literal(name), **args)
                result.append(symbol)
                continue

            split = _range.split(name)
            # remove 1 layer of bounding parentheses around ranges
            for i in range(len(split) - 1):
                if i and ':' in split[i] and split[i] != ':' and \
                        split[i - 1].endswith('(') and \
                        split[i + 1].startswith(')'):
                    split[i - 1] = split[i - 1][:-1]
                    split[i + 1] = split[i + 1][1:]
            for i, s in enumerate(split):
                if ':' in s:
                    if s[-1].endswith(':'):
                        raise ValueError('missing end range')
                    a, b = s.split(':')
                    if b[-1] in string.digits:
                        a = 0 if not a else int(a)
                        b = int(b)
                        split[i] = [str(c) for c in range(a, b)]
                    else:
                        a = a or 'a'
                        split[i] = [string.ascii_letters[c] for c in range(
                            string.ascii_letters.index(a),
                            string.ascii_letters.index(b) + 1)]  # inclusive
                    if not split[i]:
                        break
                else:
                    split[i] = [s]
            else:
                seq = True
                if len(split) == 1:
                    names = split[0]
                else:
                    names = [''.join(s) for s in cartes(*split)]
                if literals:
                    result.extend([cls(literal(s), **args) for s in names])
                else:
                    result.extend([cls(s, **args) for s in names])

        if not seq and len(result) <= 1:
            if not result:
                return ()
            return result[0]

        return tuple(result)
    else:
        for name in names:
            result.append(symbols(name, **args))

        return type(names)(result)
Create a new MetaData object.
dataset/ETHPy150Open sympy/sympy/sympy/core/symbol.py/symbols--crossover with--dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/sql/schema.py/MetaData.__init__