class School():
    def __init__(self, name, roster = {}):
        self.name = name
        self.roster = roster

    def add_student(self, student, grade):
        if self.roster.get(grade):
            self.roster[grade].append(student)
        else:
            self.roster[grade] = [student]
            
    def grade(self, grade):
        return self.roster.get(grade)
    
    def clear(self):
        self.roster = {}
        
    def sort_roster(self):
        for x in self.roster.values():
            x.sort()
        return self.roster
558b9594b3845791e59776afc9e9df4ba9ae7906
class School:
    <mask token>
    <mask token>
    <mask token>
    <mask token>
    <mask token>

class School:

    def __init__(self, name, roster={}):
        self.name = name
        self.roster = roster
    <mask token>
    <mask token>
    <mask token>
    <mask token>

class School:

    def __init__(self, name, roster={}):
        self.name = name
        self.roster = roster
    <mask token>

    def grade(self, grade):
        return self.roster.get(grade)

    def clear(self):
        self.roster = {}

    def sort_roster(self):
        for x in self.roster.values():
            x.sort()
        return self.roster

class School:

    def __init__(self, name, roster={}):
        self.name = name
        self.roster = roster

    def add_student(self, student, grade):
        if self.roster.get(grade):
            self.roster[grade].append(student)
        else:
            self.roster[grade] = [student]

    def grade(self, grade):
        return self.roster.get(grade)

    def clear(self):
        self.roster = {}

    def sort_roster(self):
        for x in self.roster.values():
            x.sort()
        return self.roster

class School():
    def __init__(self, name, roster = {}):
        self.name = name
        self.roster = roster

    def add_student(self, student, grade):
        if self.roster.get(grade):
            self.roster[grade].append(student)
        else:
            self.roster[grade] = [student]
            
    def grade(self, grade):
        return self.roster.get(grade)
    
    def clear(self):
        self.roster = {}
        
    def sort_roster(self):
        for x in self.roster.values():
            x.sort()
        return self.roster