Minor fix in docstring

Author: JeanVanDyk

causalpy/pymc_models.py

@@ -600,11 +600,11 @@ def build_model(self, t, y, coords, effect, span, grain_season):
             # --- Likelihood ---
             pm.Normal("y_hat", mu=mu, sigma=2, observed=y)
 
-    def fit(self, t, y, coords, effect=[], span=None, grain_season=1, n=None):
+    def fit(self, t, y, coords, effect=[], span=None, grain_season=1):
         """
         Draw samples from posterior distribution
         """
         self.build_model(t, y, coords, effect, span, grain_season)
         with self:
-            self.idata = pm.sample(n, **self.sample_kwargs)
+            self.idata = pm.sample(**self.sample_kwargs)
         return self.idata