Streamlining domain arg to be first

nifty6/field.py

@@ -283,7 +283,7 @@ class Field(Operator):
             raise TypeError("The multiplier must be an instance of " +
                             "the Field class")
         from .operators.outer_product_operator import OuterProduct
-        return OuterProduct(self, x.domain)(x)
+        return OuterProduct(x.domain, self)(x)
 
     def vdot(self, x, spaces=None):
         """Computes the dot product of 'self' with x.

nifty6/operators/outer_product_operator.py

@@ -27,12 +27,12 @@ class OuterProduct(LinearOperator):
 
     Parameters
     ---------
-    field: Field,
     domain: DomainTuple, the domain of the input field
+    field: Field
     ---------
     """
-    def __init__(self, field, domain):
-        self._domain = domain
+    def __init__(self, domain, field):
+        self._domain = DomainTuple.make(domain)
         self._field = field
         self._target = DomainTuple.make(
             tuple(sub_d for sub_d in field.domain._dom + domain._dom))