presto-main/src/main/java/io/prestosql/sql/planner/plan/WindowNode.java/Function/equals
class Function:        @Override
        public boolean equals(Object obj)
        {
            if (this == obj) {
                return true;
            }
            if (obj == null || getClass() != obj.getClass()) {
                return false;
            }
            Function other = (Function) obj;
            return Objects.equals(this.resolvedFunction, other.resolvedFunction) &&
                    Objects.equals(this.arguments, other.arguments) &&
                    Objects.equals(this.frame, other.frame) &&
                    this.ignoreNulls == other.ignoreNulls;
        }