Add infix C«(elem)», infix C«∈», infix C«∉» to operators

Author: lizmat

doc/Language/operators.pod6

@@ -2183,6 +2183,38 @@ Note that setting $*TOLERANCE = 0 will cause all comparisons to fail.
         say 1 =~= 1;          # OUTPUT: «False␤»
     }
 
+=head2 infix C«(elem)», infix C«∈»
+
+    multi sub infix:<(elem)>($a,$b --> Bool:D)
+    multi sub infix:<∈>($a,$b --> Bool:D)
+
+X<Membership operator>.
+
+Returns C<True> if C<$a> is an B<element> of C<$b>.
+
+    =begin code
+    say 2 (elem) (1, 2, 3); # OUTPUT: «True␤»
+    say 4 ∈ (1, 2, 3); # OUTPUT: «False␤»
+    =end code
+
+C«∈» is equivalent to C«(elem)», at codepoint U+2208 (ELEMENT OF).
+
+=head2 infix C«∉»
+
+    multi sub infix:<∉>($a,$b --> Bool:D)
+
+X<Non-membership operator>.
+
+Returns C<True> if C<$a> is B<not> an B<element> of C<$b>.  Equivalent to
+C<!(elem)>.
+
+    =begin code
+    say 4 ∉ (1, 2, 3); # OUTPUT: «True␤»
+    say 2 !(elem) (1, 2, 3); # OUTPUT: «False␤»
+    =end code
+
+C«∉» is codepoint U+2209 (NOT AN ELEMENT OF).
+
 =head1 Tight AND precedence
 
 =head2 infix C«&&»
@@ -3127,28 +3159,6 @@ This summary those operators are included for completeness.
 
 =head2 Operators that return C<Bool>
 
-=head3 infix (elem)
-
-X<Membership operator>.
-
-Returns C<True> if C<$a> is an B<element> of C<$b>.
-
-=head3 infix ∈
-
-Alternate X<membership operator>, at codepoint U+2208 (ELEMENT OF).
-
-Equivalent to L«(elem)|/routine/(elem)»,
-
-=head3 infix !(elem)
-
-X<Non-membership operator>.
-
-Returns C<True> if C<$a> is B<not an element> of C<$b>.
-
-=head3 infix ∉
-
-Alternate X<non-membership operator>, at codepoint U+2209 (NOT AN ELEMENT OF).
-
 =head3 infix (cont)
 
 X<Contains operator>.