code: def _call_structure(mname, ename, sname, name, workdir, seed, ntaxa, nsites, kpop, rep):
      
      ## create call string
      outname = os.path.join(workdir, "{}-K-{}-rep-{}".format(name, kpop, rep))
  
      cmd = ["structure", 
             "-m", mname, 
             "-e", ename, 
             "-K", str(kpop),
             "-D", str(seed), 
             "-N", str(ntaxa), 
             "-L", str(nsites),
             "-i", sname, 
             "-o", outname]
  
      ## call the shell function
      proc = subprocess.Popen(cmd,
                              stdout=subprocess.PIPE, 
                              stderr=subprocess.STDOUT)
      comm = proc.communicate()
  
      ## cleanup
      oldfiles = [mname, ename, sname]
      for oldfile in oldfiles:
          if os.path.exists(oldfile):
              os.remove(oldfile)
      return comm
docs: make the subprocess call to structure