>>> from mostratge import es_decreixent

---- inici

>>> r = es_decreixent(2, 3, 0.05)
>>> r[0]
False
>>> round(r[1], 2)
2.35

>>> r = es_decreixent(0, 2, 0.01)
>>> r[0]
True
>>> r[1]
0.0

---- fi

>>> r = es_decreixent(-0.5, 0, 0.01)
>>> r[0]
False
>>> r[1]
-0.49

>>> r = es_decreixent(2, 3, 0.001)
>>> r[0]
False
>>> round(r[1], 3)
2.292

>>> r = es_decreixent(2.2, 3, 0.0001)
>>> r[0]
False
>>> round(r[1], 4)
2.2911

>>> r = es_decreixent(-0.3, 1, 0.001)
>>> r[0]
False
>>> r[1]
-0.299