Define a function called only uses_letters_from() that takes two strings and returns True if the first string only contains characters that are also in the second string. Or to put it another way: it should return False if there are any characters in the first string that are not in the second string (Note: it's okay if there are characters in the second string that aren't in the first string.) For example,

only uses_letters_from (\"boffo\", \"foobar\") should return True, but only_uses_letters_from (\"zaxy\", \"xyzzy\") should return False

Hint: we recommend using the in operator here, as introduced in Reading Assignment 06: this is not the same thing as the \"in\" that shows up as part of the start of a for loop.