--- a
+++ b/third_party/seqan.cmake
@@ -0,0 +1,21 @@
+#https://seqan.readthedocs.io/en/seqan-v2.0.2/BuildManual/IntegrationWithYourOwnBuildSystem.html
+if (NOT EXISTS ${CMAKE_CURRENT_LIST_DIR}/seqan)
+
+message("build new seqan ")
+ExternalProject_Add(
+  seqan
+  PREFIX ${CMAKE_CURRENT_LIST_DIR}/seqan
+  GIT_REPOSITORY https://github.com/seqan/seqan.git
+  CONFIGURE_COMMAND "" 
+  BUILD_COMMAND "" 
+  INSTALL_COMMAND ""
+)
+
+else()
+
+add_custom_target(seqan)
+
+endif()
+set (CMAKE_CXX_FLAGS " ${CMAKE_CXX_FLAGS} -DSEQAN_ENABLE_DEBUG=0 -DSEQAN_ENABLE_TESTING=0 -DSEQAN_HAS_ZLIB=1 " )
+
+MESSAGE( STATUS "new target: seqan" )