def METHOD_NAME(alltypes):
    val = "2015-01-01 00:00:00"
    expr = alltypes.i > val
    op = expr.op()
    assert op.right.dtype is dt.string
    expr2 = val < alltypes.i
    op = expr2.op()
    assert isinstance(op, ops.Greater)
    assert op.right.dtype is dt.string