src/sage/modular/modform_hecketriangle/abstract_space.py: Fix up import

Author: Matthias Koeppe

src/sage/modular/modform_hecketriangle/abstract_space.py

@@ -16,6 +16,7 @@
 # ****************************************************************************
 from sage.matrix.constructor import matrix
 from sage.misc.cachefunc import cached_method
+from sage.misc.lazy_import import lazy_import
 from sage.modules.free_module_element import is_FreeModuleElement
 from sage.modules.free_module_element import vector
 from sage.rings.infinity import infinity