solving %s when the argument is not real or imaginary.

Raise code

separatevars(Abs(arg)).rewrite(Piecewise) if arg.has(*symbols)
                else Abs(arg))
            if was == fi:
                break

        for e in fi.find(Abs):
            if e.has(*symbols):
                raise NotImplementedError('solving %s when the argument '
                    'is not real or imaginary.' % e)

        # arg
        fi = fi.replace(arg, lambda a: arg(a).rewrite(atan2).rewrite(atan))

        # save changes
        f[i] = fi

    # see if re