union_rule for Piecewise (#207)

Author: jishnub

src/Spaces/Spaces.jl

@@ -7,12 +7,12 @@ include("PolynomialSpace.jl")
 
 # union_rule dictates how to create a space that both spaces can be converted to
 # in this case, it means
-function union_rule(s1::PiecewiseSpace{S1},s2::PiecewiseSpace{S2}) where {S1<:Tuple{Vararg{PolynomialSpace}},
-                    S2<:Tuple{Vararg{PolynomialSpace}}}
+function union_rule(s1::PiecewiseSpace{<:TupleOrVector{PolynomialSpace}},
+        s2::PiecewiseSpace{<:TupleOrVector{PolynomialSpace}})
     PiecewiseSpace(map(Space,merge(domain(s1),domain(s2)).domains))
 end
 
-function union_rule(s1::PiecewiseSpace{S1},s2::PolynomialSpace) where S1<:Tuple{Vararg{PolynomialSpace}}
+function union_rule(s1::PiecewiseSpace{<:TupleOrVector{PolynomialSpace}}, s2::PolynomialSpace)
     PiecewiseSpace(map(Space,merge(domain(s1),domain(s2)).domains))
 end