Circular Buffer in Python Part 2

circular_buffer.py

def size(self):
    """Return the size of the CircularBuffer
    Runtime: O(1) Space: O(1)"""
    if self.tail >= self.head:
        return self.tail - self.head
    return self.max_size - self.head - self.tail

def is_empty(self):
    """Return True if the head of the CircularBuffer is equal to the tail,
    otherwise return False
    Runtime: O(1) Space: O(1)"""
    return self.tail == self.head

def is_full(self):
    """Return True if the tail of the CircularBuffer is one before the head,
    otherwise return False
    Runtime: O(1) Space: O(1)"""
    return self.tail == (self.head-1) % self.max_size