diff --git a/sumpy/expansion/__init__.py b/sumpy/expansion/__init__.py
index eeaaa650ecf776c276840a83fd8ff080214f82bb..d3dfbccb1de7edfd262f7daa5eb920b24ca937da 100644
--- a/sumpy/expansion/__init__.py
+++ b/sumpy/expansion/__init__.py
@@ -402,6 +402,15 @@ class LinearPDEBasedExpansionTermsWrangler(ExpansionTermsWrangler):
         return defaultdict(list, matrix_rows), reconstruct_matrix_with_rscale, \
             use_reconstruct
 
+    def get_pde(self):
+        r"""
+        Returns a PDE. A PDE stores a dictionary of (mi, coeff)
+        where mi is the multi-index of the  derivative and coeff is the
+        coefficient
+        """
+
+        raise NotImplementedError
+
     @memoize_method
     def get_stored_ids_and_coeff_mat(self):
         from six import iteritems
@@ -478,15 +487,6 @@ class LinearPDEBasedExpansionTermsWrangler(ExpansionTermsWrangler):
 
         return stored_identifiers, coeff_matrix, reconstruct_matrix
 
-    def get_pde(self):
-        r"""
-        Returns a PDE. A PDE stores a dictionary of (mi, coeff)
-        where mi is the multi-index of the  derivative and coeff is the
-        coefficient
-        """
-
-        raise NotImplementedError
-
 
 class LaplaceExpansionTermsWrangler(LinearPDEBasedExpansionTermsWrangler):