remove unused code

amodem/dsp.py

@@ -15,7 +15,6 @@ class Filter(object):
         self.x_state = [0] * len(self.b)
         self.y_state = [0] * (len(self.a) + 1)
 
-
     def __call__(self, x):
         x_, y_ = self.x_state, self.y_state
         for v in x:
@@ -138,10 +137,6 @@ class MODEM(object):
         ])
 
 
-def power(x):
-    return np.dot(x.conj(), x).real / len(x)
-
-
 def exp_iwt(freq, n):
     iwt = 2j * np.pi * freq * np.arange(n) * Ts
     return np.exp(iwt)