Function op_left 

pub fn op_left(stack: &mut Stack) -> bool

OP_LEFT: Extracts a left substring from the second-to-top item on the stack

Example: OP_LEFT([s, n]) -> [s[..n-1]] if n < len(s) OP_LEFT([s, n]) -> [s] if n >= len(s)

Arguments

• stack - mutable reference to the stack