Merge pull request #6 from chrhansk/feature-for-loop-with-by-argument

Add support for "for-from loops" with "by" argument

grammar.js

@@ -129,7 +129,8 @@ module.exports = grammar(Python, {
     _compound_statement: ($, original) =>
       choice(
         original,
-        $.def_statement,
+        $.DEF_statement,
+        $.IF_statement,
         $.cdef_statement,
         $.ctypedef_statement,
         $.property_definition,
@@ -148,7 +149,7 @@ module.exports = grammar(Python, {
         ),
       ),
 
-    def_statement: $ =>
+    DEF_statement: $ =>
       seq(
         "DEF",
         field("name", $.identifier),
@@ -157,6 +158,28 @@ module.exports = grammar(Python, {
         $._newline,
       ),
 
+    IF_statement: $ => seq(
+      "IF",
+      field("condition", $.expression),
+      ":",
+      field("consequence", $._suite),
+      repeat(field("alternative", $.ELIF_clause)),
+      optional(field("alternative", $.ELSE_clause)),
+    ),
+
+    ELIF_clause: $ => seq(
+      "ELIF",
+      field("condition", $.expression),
+      ":",
+      field("consequence", $._suite),
+    ),
+
+    ELSE_clause: $ => seq(
+      "ELSE",
+      ":",
+      field("body", $._suite),
+    ),
+
     cdef_statement: $ =>
       seq(
         choice("cdef", "cpdef"),
@@ -729,6 +752,10 @@ module.exports = grammar(Python, {
           choice("in", "from"),
         )),
         field("right", $._expressions),
+        optional(seq(
+          "by",
+          $._expressions,
+        )),
         ":",
         field("body", $._suite),
         field("alternative", optional($.else_clause)),