Retrieves the full set of available constraints and iterate over them, validating
        that they exist and that they are not causing unresolvable conflicts.

        :return: True if the constraints are satisfied by the resolution provided
        :raises: :exc:`pipenv.exceptions.DependencyConflict` if the constraints dont exist

def validate_constraints(self):
        """
        Retrieves the full set of available constraints and iterate over them, validating
        that they exist and that they are not causing unresolvable conflicts.

        :return: True if the constraints are satisfied by the resolution provided
        :raises: :exc:`pipenv.exceptions.DependencyConflict` if the constraints dont exist
        """
        constraints = self.get_constraints()
        for constraint in constraints:
            try:
                constraint.check_if_exists(False)
            except Exception:
                from pipenv.exceptions import DependencyConflict
                msg = (
                    "Cannot resolve conflicting version {0}{1} while {1}{2} is "
                    "locked.".format(
                        self.name, self.updated_specifier, self.old_name, self.old_specifiers
                    )
                )
                raise DependencyConflict(msg)
        return True