def __init__(self, e, db=None, tx=None):
assert (db is not None or tx is not None),"<STR_LIT>"<EOL>self._eid   = int(e)<EOL>self._db    = db or tx.db<EOL>self._tx    = tx<EOL>self._txid  = -<NUM_LIT:1> if not tx else tx.txid<EOL>self._dict  = None<EOL>
Represents an entity in the db,
        or a tempid in a non-committed state.

        >>> person = E(1, db)
        >>> person.eid
        1

        Fetch all attributes, behave like a dict
        >>> person.items()

        Iterator just like a dictionary
        >>> person.iteritems()

        Access attribute as an attribute
        >>> person['person/name']
        >>> person.get('person/name')

        Access ns attribute with dot notation
        >>> person.person