iPython
In [1]: {}
Out[1]: {}
In [2]: dict()
Out[2]: {}
In [3]: import dis
In [4]: dis.dis('{}')
1 0 BUILD_MAP 0
2 RETURN_VALUE
In [5]: dis.dis('dict()')
1 0 LOAD_NAME 0 (dict)
2 CALL_FUNCTION 0
4 RETURN_VALUE
