takes a number of bytes as an argument and returns the most suitable human
    readable unit conversion.

def convert(b):
    '''
    takes a number of bytes as an argument and returns the most suitable human
    readable unit conversion.
    '''
    if b > 1024**3:
        hr = round(b/1024**3)
        unit = "GB"
    elif b > 1024**2:
        hr = round(b/1024**2)
        unit = "MB"
    else:
        hr = round(b/1024)
        unit = "KB"
    return hr, unit