Returns .true if the character at position n matches any character of the string chars. Returns .false if the character does not match any of the characters in the reference set. The argument n must be a positive whole number.

"a+b"~matchChar(2, "+-*/")           -->    1
"a+b"~matchChar(1, "+-*/")           -->    0
"Friday"~matchChar(3, "aeiou")       -->    1
"FRIDAY"~matchChar(3, "aeiou")       -->    0