Need help implementing this function based on the specifications below.

def average_grade(adict): """ Returns the average grade among all students.

The dictionary adict has netids for keys and numbers 0-100 for values. These represent the grades that the students got on the exam. This function averages those grades and returns a value.

Examples: average_grade({'wmw2' : 55, 'abc3' : 90, 'jms45': 86}) returns (55+90+86)/3 = 77 average_grade({'wmw2' : 55}) returns 55 average_grade({}) returns 0 Parameter adict: the dictionary of grades Precondition: adict is dictionary mapping strings to ints """ pass