function substring(original, start [, length])

substring() returns a substring of the original, with a 0-based index start and length. If length is omitted, it returns a substring from start until the end of the string.

Arguments:
original: An expression that returns a string
start: An expression that returns a positive number
length: An expression that returns a positive number

Example Query:
    RETURN substring("hello", 1, 3), substring("hello", 2)