--- a
+++ b/deeptrio/dt_constants.py
@@ -0,0 +1,60 @@
+# Copyright 2017 Google LLC.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice,
+#    this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# 3. Neither the name of the copyright holder nor the names of its
+#    contributors may be used to endorse or promote products derived from this
+#    software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+"""Common constants shared across DeepVariant's codebase.
+
+This file is for very general constants in the code that end up needing to be
+accessed in a variety of places, often in live code as well as throughout the
+code in tests.
+"""
+
+# Default width [in basepairs] for our DeepVariant data tensor.
+PILEUP_DEFAULT_WIDTH = 221
+
+# Default height [in rows] for our DeepVariant data tensor.
+PILEUP_DEFAULT_HEIGHT = 300
+
+# Default height [in rows] for our DeepVariant parent data tensor.
+PILEUP_DEFAULT_HEIGHT_PARENT = 100
+
+# Default height [in rows] for our DeepVariant child data tensor.
+PILEUP_DEFAULT_HEIGHT_CHILD = 100
+
+# Not a default because it's hard-coded into the code.
+PILEUP_NUM_CHANNELS = 6
+
+# The dimensions of a pileup image tensor as height x width x rank.
+PILEUP_DEFAULT_DIMS = [
+    PILEUP_DEFAULT_HEIGHT,
+    PILEUP_DEFAULT_WIDTH,
+    PILEUP_NUM_CHANNELS,
+]
+
+# Number of classes represented in the data set. The three classes are
+# homozygous reference (0), heterozygous (1) and homozygous alternative (2).
+NUM_CLASSES = 3