@count(tab, value)
@count(map, value)
@count(string, value)
computes the number of times the second argument appears in the first argument. For a map, the second argument refers to a value stored in the dictionary. For a string, the second argument must be a string and the call returns the number of occurences of the first character in the first string:
@count("abacaa", "a")
4
.