in

x in xs asks whether the list (or text) holds the value, yes or no:

2 in [5 2]           // yes
"ell" in "hello"     // yes

Where it stands comes from index_of, a position counted from 1: [5 2].index_of(2) is 2 (see indexing). xs.has(x) is the same test as x in xs.

keyword for indexing, deep property access and as function argument

# not yet: print … in cyrillic (card print-in-script)
print chars in "hello"
print name in peter{name="James"}
to print string in cyrillic: map string's chars to cyrillic