message: Modify the correct signature to operator== and !=
diff: @@ -64,7 +64,7 @@ class Persistence_interval_common {
  * fields: birth, death, dimensiona and arith_element_ are taken into account
  * and they all have to be equal for two pairs to be equal.
  **/
  - inline bool operator==(const Persistence_interval_common& i2) {
  + bool operator==(const Persistence_interval_common& i2) const {
  return ((this->birth_ == i2.birth_) && (this->death_ == i2.death_) && (this->dimension_ == i2.dimension_) &&
  (this->arith_element_ == i2.arith_element_));
  }
  @@ -72,7 +72,7 @@ class Persistence_interval_common {
  /**
  * Check if two persistence paris are not equal.
  **/
  - inline bool operator!=(const Persistence_interval_common& i2) { return (!((*this) == i2)); }
  + bool operator!=(const Persistence_interval_common& i2) const { return (!((*this) == i2)); }
  /**
  * Operator to compare objects of a type Persistence_interval_common.
  