'Add value to histogram
:type value: float'

def add(self, value):

    with self.lock:
        self.sample.update(value)
        self.counter = (self.counter + 1)
        self.max = (value if (value > self.max) else self.max)
        self.min = (value if (value < self.min) else self.min)
        self.sum = (self.sum + value)
        self._update_var(value)
