https://git.ruby-lang.org/ruby.git/commit/?id=48313f129a

From 48313f129abd464c69853a66af22adbad260b82e Mon Sep 17 00:00:00 2001
From: Kazuhiro NISHIYAMA <zn@m...>
Date: Sat, 27 Apr 2019 12:21:35 +0900
Subject: Add `or nil` to call-seq of `Enumerator::ArithmeticSequence#begin`

```
% ruby -ve 'p (nil..).first'
ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-darwin18]
nil
% ruby -ve 'p (nil..).begin'
ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-darwin18]
nil
```

diff --git a/enumerator.c b/enumerator.c
index 9a0f926..76560fa 100644
--- a/enumerator.c
+++ b/enumerator.c
@@ -2936,7 +2936,7 @@ rb_arith_seq_new(VALUE obj, VALUE meth, int argc, VALUE const *argv, https://github.com/ruby/ruby/blob/trunk/enumerator.c#L2936
 }
 
 /*
- * call-seq: aseq.begin -> num
+ * call-seq: aseq.begin -> num or nil
  *
  * Returns the number that defines the first element of this arithmetic
  * sequence.
-- 
cgit v0.10.2


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