code: def pkg_config(pkg_libraries):
      
      libraries=[]
      library_dirs=[]
      include_dirs=[]
  
      # Check that we have the packages
      for pkg in pkg_libraries:
          if os.system('pkg-config --exists %s 2>/dev/null' % pkg) == 0:
              pass
          else:
              print("Could not find library {0}".format(pkg))
              sys.exit(1)
  
      # Get the pck-config flags
      if len(pkg_libraries)>0 :
          # PKG_CONFIG_ALLOW_SYSTEM_CFLAGS explicitly lists system paths.
          # On system-wide LAL installs, this is needed for swig to find lalswig.i
          for token in getoutput("PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=1 pkg-config --libs --cflags %s" % ' '.join(pkg_libraries)).split():
              if token.startswith("-l"):
                  libraries.append(token[2:])
              elif token.startswith("-L"):
                  library_dirs.append(token[2:])
              elif token.startswith("-I"):
                  include_dirs.append(token[2:])
  
      return libraries, library_dirs, include_dirs
docs: Use pkg-config to query for the location of libraries, library directories,
         and header directories
  
         Arguments:
             pkg_libries(list): A list of packages as strings
  
         Returns:
             libraries(list), library_dirs(list), include_dirs(list)