fix inverse_fn

Author: mjrodgers

src/Map.jl

@@ -199,7 +199,7 @@ function preimage_function(f::Map(HeckeMap))
 end
 
 image_fn(f::Map(HeckeMap)) = image_function(f)
-# inverse_fn(f::Map(HeckeMap)) = preimage_function(f)
+inverse_fn(f::Map(HeckeMap)) = preimage_function(f)
 
 
 ################################################################################

src/generic/imports.jl

@@ -159,6 +159,7 @@ import ..AbstractAlgebra: integral
 import ..AbstractAlgebra: internal_ordering
 import ..AbstractAlgebra: inv
 import ..AbstractAlgebra: inv!
+import ..AbstractAlgebra: inverse_fn
 import ..AbstractAlgebra: is_constant
 import ..AbstractAlgebra: is_divisible_by
 import ..AbstractAlgebra: is_domain_type

test/MapFromFunc.jl

@@ -5,7 +5,7 @@
   @test preimage(f, ZZ(1)) == 0
 
   @test image_fn(f)(ZZ(1)) == 2
-  @test preimage_function(f)(ZZ(1)) == 0
+  @test inverse_fn(f)(ZZ(1)) == 0
 
   @test preimage(f, image(f, ZZ(1))) == ZZ(1)