remove unnecessary code leftover from merge, and remove unneccesary i…

…mport detected by pyflakes

src/sage/combinat/sf/sfa.py

@@ -4977,7 +4977,6 @@ def frobenius(self, n):
         # then convert back.
         parent = self.parent()
         m = parent.realization_of().monomial()
-        from sage.combinat.partition import Partition
         dct = {lam.stretch(n): coeff for lam, coeff in m(self)}
         result_in_m_basis = m._from_dict(dct)
         return parent(result_in_m_basis)

src/sage/rings/lazy_series.py

@@ -4428,80 +4428,6 @@ def revert(self):
     plethystic_inverse = revert
     compositional_inverse = revert
 
-    def _format_series(self, formatter, format_strings=False):
-        r"""
-        Return nonzero ``self`` formatted by ``formatter``.
-
-        TESTS::
-
-            sage: h = SymmetricFunctions(ZZ).h()
-            sage: e = SymmetricFunctions(ZZ).e()
-            sage: L = LazySymmetricFunctions(tensor([h, e]))
-            sage: f = L(lambda n: sum(tensor([h[k], e[n-k]]) for k in range(n+1)))
-            sage: f._format_series(repr)
-            '(h[]#e[])
-             + (h[]#e[1]+h[1]#e[])
-             + (h[]#e[2]+h[1]#e[1]+h[2]#e[])
-             + (h[]#e[3]+h[1]#e[2]+h[2]#e[1]+h[3]#e[])
-             + (h[]#e[4]+h[1]#e[3]+h[2]#e[2]+h[3]#e[1]+h[4]#e[])
-             + (h[]#e[5]+h[1]#e[4]+h[2]#e[3]+h[3]#e[2]+h[4]#e[1]+h[5]#e[])
-             + (h[]#e[6]+h[1]#e[5]+h[2]#e[4]+h[3]#e[3]+h[4]#e[2]+h[5]#e[1]+h[6]#e[])
-             + O^7'
-        """
-        P = self.parent()
-        cs = self._coeff_stream
-        v = cs._approximate_order
-        if isinstance(cs, Stream_exact):
-            if not cs._constant:
-                m = cs._degree
-            else:
-                m = cs._degree + P.options.constant_length
-        else:
-            m = v + P.options.display_length
-
-        atomic_repr = P._internal_poly_ring.base_ring()._repr_option('element_is_atomic')
-        mons = [P._monomial(self[i], i) for i in range(v, m) if self[i]]
-        if not isinstance(cs, Stream_exact) or cs._constant:
-            if P._internal_poly_ring.base_ring() is P.base_ring():
-                bigO = ["O(%s)" % P._monomial(1, m)]
-            else:
-                bigO = ["O^%s" % m]
-        else:
-            bigO = []
-
-        from sage.misc.latex import latex
-        from sage.typeset.unicode_art import unicode_art
-        from sage.typeset.ascii_art import ascii_art
-        from sage.misc.repr import repr_lincomb
-        from sage.typeset.symbols import ascii_left_parenthesis, ascii_right_parenthesis
-        from sage.typeset.symbols import unicode_left_parenthesis, unicode_right_parenthesis
-        if formatter == repr:
-            poly = repr_lincomb([(1, m) for m in mons + bigO], strip_one=True)
-        elif formatter == latex:
-            poly = repr_lincomb([(1, m) for m in mons + bigO], is_latex=True, strip_one=True)
-        elif formatter == ascii_art:
-            if atomic_repr:
-                poly = ascii_art(*(mons + bigO), sep = " + ")
-            else:
-                def parenthesize(m):
-                    a = ascii_art(m)
-                    h = a.height()
-                    return ascii_art(ascii_left_parenthesis.character_art(h),
-                                     a, ascii_right_parenthesis.character_art(h))
-                poly = ascii_art(*([parenthesize(m) for m in mons] + bigO), sep = " + ")
-        elif formatter == unicode_art:
-            if atomic_repr:
-                poly = unicode_art(*(mons + bigO), sep = " + ")
-            else:
-                def parenthesize(m):
-                    a = unicode_art(m)
-                    h = a.height()
-                    return unicode_art(unicode_left_parenthesis.character_art(h),
-                                       a, unicode_right_parenthesis.character_art(h))
-                poly = unicode_art(*([parenthesize(m) for m in mons] + bigO), sep = " + ")
-
-        return poly
-
     def symmetric_function(self, degree=None):
         r"""
         Return ``self`` as a symmetric function if ``self`` is actually so.