[Python] Avoid keyword for positional 'phase' parameter

interfaces/cython/cantera/reactor.pyx

@@ -273,11 +273,10 @@ cdef class Reactor(ReactorBase):
         >>> gas = Solution('gri30.yaml')
         >>> r1 = Reactor(gas)
 
-        Arguments may be specified using keywords in any order:
+        Arguments may be specified using keywords:
 
-        >>> r2 = Reactor(phase=gas, energy='off',
+        >>> r2 = Reactor(gas, energy='off',
         ...              name='isothermal_reactor')
-        >>> r3 = Reactor(name='adiabatic_reactor', phase=gas)
 
         """
         super().__init__(phase, clone=clone, name=name, **kwargs)
@@ -883,7 +882,7 @@ cdef class ReactorSurface(ReactorBase):
         self.rbase = self._rbase.get()
         self.surface = <CxxReactorSurface*>(self.rbase)
 
-    def __init__(self, phase=None, r=None, clone=None, *,
+    def __init__(self, phase=None, r=None, *, clone=None,
                  name="(none)", A=None, node_attr=None):
         super().__init__(phase, name=name)
 

samples/python/kinetics/shock_tube.py

@@ -52,7 +52,7 @@ for k, m in enumerate(models):
     gas = ct.Solution(file, name=models[m])
     X = {'H2O2':X_H2O2, 'H2O':X_H2O, 'O2':X_O2, 'CO2':X_CO2, 'AR':X_Ar}
     gas.TPX = 1196, 2.127*ct.one_atm, X
-    r = ct.Reactor(phase=gas, energy="on", clone=False)
+    r = ct.Reactor(gas, energy="on", clone=False)
     reactorNetwork = ct.ReactorNet([r])
     timeHistory = ct.SolutionArray(gas, extra=['t'])
     estIgnitDelay = 1

samples/python/reactors/non_ideal_shock_tube.py

@@ -117,7 +117,7 @@ real_gas.set_equivalence_ratio(phi=1.0, fuel='c12h26',
 
 # Create a reactor object and add it to a reactor network
 # In this example, this will be the only reactor in the network
-r = ct.Reactor(phase=real_gas, clone=False)
+r = ct.Reactor(real_gas, clone=False)
 reactor_network = ct.ReactorNet([r])
 time_history_RG = ct.SolutionArray(real_gas, extra=['t'])
 
@@ -154,7 +154,7 @@ ideal_gas.TP = reactor_temperature, reactor_pressure
 ideal_gas.set_equivalence_ratio(phi=1.0, fuel='c12h26',
                                 oxidizer={'o2': 1.0, 'n2': 3.76})
 
-r = ct.Reactor(phase=ideal_gas, clone=False)
+r = ct.Reactor(ideal_gas, clone=False)
 reactor_network = ct.ReactorNet([r])
 time_history_IG = ct.SolutionArray(ideal_gas, extra=['t'])
 
@@ -231,7 +231,7 @@ for i, temperature in enumerate(T):
     real_gas.TP = reactor_temperature, reactor_pressure
     real_gas.set_equivalence_ratio(phi=1.0, fuel='c12h26',
                                    oxidizer={'o2': 1.0, 'n2': 3.76})
-    r = ct.Reactor(phase=real_gas, clone=False)
+    r = ct.Reactor(real_gas, clone=False)
     reactor_network = ct.ReactorNet([r])
 
     # create an array of solution states
@@ -263,7 +263,7 @@ for i, temperature in enumerate(T):
     ideal_gas.TP = reactor_temperature, reactor_pressure
     ideal_gas.set_equivalence_ratio(phi=1.0, fuel='c12h26',
                                     oxidizer={'o2': 1.0, 'n2': 3.76})
-    r = ct.Reactor(phase=ideal_gas, clone=False)
+    r = ct.Reactor(ideal_gas, clone=False)
     reactor_network = ct.ReactorNet([r])
 
     # create an array of solution states