diff --git a/fimfarchive/mappers.py b/fimfarchive/mappers.py
new file mode 100644
index 0000000..df44e25
--- /dev/null
+++ b/fimfarchive/mappers.py
@@ -0,0 +1,43 @@
+"""
+Mappers for Fimfarchive.
+"""
+
+
+#
+# Fimfarchive, preserves stories from Fimfiction.
+# Copyright (C) 2015  Joakim Soderlund
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+
+class Mapper:
+    """
+    Callable which maps something to something else.
+    """
+
+    def __call__(self, *args, **kwargs):
+        raise NotImplementedError()
+
+
+class StaticMapper(Mapper):
+    """
+    Returns the supplied value for any call.
+    """
+
+    def __init__(self, value=None):
+        self.value = value
+
+    def __call__(self, *args, **kwargs):
+        return self.value
diff --git a/tests/test_mappers.py b/tests/test_mappers.py
new file mode 100644
index 0000000..9b36280
--- /dev/null
+++ b/tests/test_mappers.py
@@ -0,0 +1,68 @@
+"""
+Mapper tests.
+"""
+
+
+#
+# Fimfarchive, preserves stories from Fimfiction.
+# Copyright (C) 2015  Joakim Soderlund
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+
+import pytest
+
+from fimfarchive.mappers import StaticMapper
+
+
+class TestStaticMapper:
+    """
+    StaticMapper tests.
+    """
+
+    @pytest.fixture
+    def value(self):
+        """
+        Returns a unique instance.
+        """
+        return object()
+
+    def test_value(self, value):
+        """
+        Tests returns the supplied value.
+        """
+        mapper = StaticMapper(value)
+        assert mapper() is value
+
+    def test_default_value(self):
+        """
+        Tests `None` is returned by default.
+        """
+        mapper = StaticMapper()
+        assert mapper() is None
+
+    def test_args(self, value):
+        """
+        Tests callable ignores args.
+        """
+        mapper = StaticMapper(value)
+        assert mapper(1, 2, 3) is value
+
+    def test_kwargs(self, value):
+        """
+        Tests callable ignores kwargs.
+        """
+        mapper = StaticMapper(value)
+        assert mapper(a=1, b=2) is value