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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_grade(self):
 """Gets the grade in this entry if the grading system is based on grades. return: (osid.grading.Grade) - the grade raise: IllegalState - ``is_graded()`` is ``false`` or ``GradeSystem.isBasedOnGrades()`` is ``false`` raise: OperationFailed - unable to complete request *compliance: mandatory -- This method must be implemented.* """

        grade_system = self.get_gradebook_column().get_grade_system()

        for grade in grade_system.get_grades():
            if str(grade.ident) == self._my_map['gradeId']:
                return grade
        raise errors.IllegalState('gradeId does not exist in this GradeSystem')