Michael Hudson <mwh21@cam.ac.uk>:
Removed PyErr_BadArgument() calls and replaced them with more useful
error messages.
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 9a09c7d..7966e0a 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -540,7 +540,9 @@
 	int size;
 	arrayobject *np;
 	if (!is_arrayobject(bb)) {
-		PyErr_BadArgument();
+		PyErr_Format(PyExc_TypeError,
+		     "can only append array (not \"%.200s\") to array",
+			     bb->ob_type->tp_name);
 		return NULL;
 	}
 #define b ((arrayobject *)bb)
@@ -613,7 +615,9 @@
 		}
 	}
 	else {
-		PyErr_BadArgument();
+		PyErr_Format(PyExc_TypeError,
+	     "can only assign array (not \"%.200s\") to array slice",
+			     v->ob_type->tp_name);
 		return -1;
 	}
 	if (ilow < 0)
@@ -821,7 +825,8 @@
 	char tmp[sizeof(double)]; /* Assume that's the max item size */
 
 	if (args != NULL) {
-		PyErr_BadArgument();
+		PyErr_SetString(PyExc_TypeError,
+		     "<array>.reverse requires exactly 0 arguments");
 		return NULL;
 	}