class Student:
    def __init__(self, first_name, last_name, grades=None):
        self.first_name = first_name
        self.last_name = last_name
        self.grades = [] if grades is None else grades

    @property
    def full_name(self):
        return f'{self.first_name} {self.last_name}'

    @property
    def email(self):
        return f'{self.first_name}{self.last_name[0]}@codewars.com'

    @property
    def grade_average(self):
        return sum(self.grades) / len(self.grades)

    def assess(self):
        if self.grade_average >= 90:
            return "A"
        if self.grade_average >= 80:
            return "B"
        if self.grade_average >= 70:
            return "C"
        if self.grade_average >= 65:
            return "D"
        return "F"

package cat;
public class kata{
  public static int doubleValue(int x) {
    return x * 2;
  }
}