>>> import time
>>> def jdn(): 
...    year, month, day = time.gmtime()[:3]
...    a = (14 - month) // 12
...    y = year + 4800 - a
...    m = month + (12 * a) - 3
...    p = day + (((153 * m) + 2) // 5) + (365 * y)
...    q = (y // 4) - (y // 100) + (y // 400) - 32045
...    return p + q
... 
>>> jdn()
2454845
>>> def mjd(): 
...    return jdn() - 2400000.5
... 
>>> mjd()
54844.5
>>> 

no text.

>>> import math
>>> def mjdn(): 
...    return int(math.floor(jdn() - 2400000.5))
... 
>>> mjdn()
54844