def METHOD_NAME(self, i):
    r"""
    Return `\varepsilon_i` of ``self``.
    EXAMPLES::
        sage: C = crystals.Tableaux(['A',[1,2]], shape=[2,1])
        sage: c = C.an_element(); c
        [[-2, -2], [-1]]
        sage: c.epsilon(2)
        0
        sage: c.epsilon(0)
        0
        sage: c.epsilon(-1)
        0
    """
    string_length = 0
    x = self
    while True:
        x = x.e(i)
        if x is None:
            return string_length
        else:
            string_length += 1