lisp interpreter for arithmetic operations

parse.py

def read_from_tokens(tokens):
    if len(tokens) == 0: raise SyntaxError("unexpected EOF while reading")
    token = tokens.pop(0)
    if token == '(':
        L = []
        while tokens[0] != ')':
            L.append(read_from_tokens(tokens))
            print(L)
        tokens.pop(0) # pop off ')'
        return L
    elif token == ')': raise SyntaxError('unexpected')
    else: return atom(token)
    
def atom(token):
    try: return int(token)
    except ValueError:
        try: return float(token)
        except ValueError:
            return Symbol(token)

Symbol = str
List = list
Number = (int, float)