presto-main/src/main/java/io/prestosql/sql/planner/Symbol.java/Symbol/equals
class Symbol:    @Override
    public boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        Symbol symbol = (Symbol) o;

        if (!name.equals(symbol.name)) {
            return false;
        }

        return true;
    }