def configure_args(self):
    spec = self.spec
    args = ['--enable-build-libxml2', '--enable-build-libxslt']
    if ('~mpi' in spec):
        args += ['--enable-serial']
    return args
def configure_args(self):
    spec = self.spec
    args = ['--enable-build-libxml2', '--enable-build-libxslt']
    if ('~mpi' in spec):
        args += ['--enable-serial']
    return args