maketrans(...)
    str.maketrans(x[, y[, z]]) -> dict (static method)
    
    Return a translation table usable for str.translate().
    If there is only one argument, it must be a dictionary mapping Unicode
    ordinals (integers) or characters to Unicode ordinals, strings or None.
    Character keys will be then converted to ordinals.
    If there are two arguments, they must be strings of equal length, and
    in the resulting dictionary, each character in x will be mapped to the
    character at the same position in y. If there is a third argument, it
    must be a string, whose characters will be mapped to None in the result.

  
>>> 'abc'.maketrans('123', '456')
{49: 52, 50: 53, 51: 54}
>>>

  
>>> c = 1+2j
>>> dir(c)
['__abs__', '__add__', '__bool__', '__class__', '__delattr__', '__dir__', '__divmod__', '__doc__', '__eq__', '__float__', '__floordiv__', '__format__', '__ge__', '__getattribute__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__int__', '__le__', '__lt__', '__mod__', '__mul__', '__ne__', '__neg__', '__new__', '__pos__', '__pow__', '__radd__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rmod__', '__rmul__', '__rpow__', '__rsub__', '__rtruediv__', '__setattr__', '__sizeof__', '__str__', '__sub__', '__subclasshook__', '__truediv__', 'conjugate', 'imag', 'real']
>>>

  
>>> c * [1, 2, 3]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can't multiply sequence by non-int of type 'complex'
>>> 

 # -*- coding:utf-8 -*-
settings = {"db_kind": "RDBMS"}  # config
    
class RDBMSProvider:
    pass
    
class KeyValueProvider:
    pass
    
class Meta(type):
    
    def __new__(cls, name, base, dct):
        if settings["db_kind"] == "RDBMS":
            dct["_provider"] = RDBMSProvider()
        else:
            dct["_provider"] = KeyValueProvider()
    
        # cls._provider - protected attribute
   
        return super(Meta, cls).__new__(cls, name, base, dct)
    
class BaseDataAdapter(object):
    __metaclass__ = Meta
    
    @classmethod
    def get_db_kind(cls):
        return cls._provider.__class__.__name__
    
class DataAdapter(BaseDataAdapter):
    pass
    
print DataAdapter.get_db_kind()