code: def parse(expression):
      
      result = []
      current = ""
      for i in expression:
          if i.isdigit() or i == '.':
              current += i
          else:
              if len(current) > 0:
                  result.append(current)
                  current = ""
              if i in __operators__ or i in __parenthesis__:
                  result.append(i)
              else:
                  raise Exception("invalid syntax " + i)
  
      if len(current) > 0:
          result.append(current)
      return result
docs: Return array of parsed tokens in the expression
  
      expression String: Math expression to parse in infix notation