Bind of x (y …) M

From: stackoverflow.com/questions/12870489/regex-to-match-a-word-with-unique-non-repeating-characters

Source: stackoverflow.com/questions/42004440/regex-to-match-4-letters-in-a-string

stackoverflow.com/questions/30648699/regular-expression-to-match-at-least-two-special-characters-in-any-order