title: efetch with too many accession number
body: <p>I have a problem with the following script. I´m trying to submit 110 000 NCBI accession IDS to recover fasta sequences but i don´t get them all since (guess need some sort of batch submission mode or will not get all sequences). i think i have to use batch mode but not sure how to do it ?
  Here is the script i´m using.</p>
  
  <pre><code>import sys
  from Bio import Entrez
  from Bio import SeqIO
  
  
  #define email for entrez login
  db           = "nuccore"
  Entrez.email = "someone@email.com"
  
  #load accessions from arguments
  if len(sys.argv[1:]) &gt; 1:
    accs = sys.argv[1:]
  else: #load accesions from stdin  
    accs = [ l.strip() for l in sys.stdin if l.strip() ]
  #fetch
  sys.stderr.write( "Fetching %s entries from GenBank: %s\n" % (len(accs), ", ".join(accs[:10])))
  for i,acc in enumerate(accs):
    try:
      sys.stderr.write( " %9i %s          \r" % (i+1,acc))  
      handle = Entrez.efetch(db=db, rettype="fasta", id=acc)
      seq_record = SeqIO.read(handle, "fasta")
  
      if (len(seq_record.seq) &gt; 0):
        header = "&gt;" + seq_record.description + " Len:" , len(seq_record.seq)
        print(",".join(str(x) for x in header))
        print(seq_record.seq)
    except:
      sys.stderr.write( "Error! Cannot fetch: %s        \n" % acc)
  </code></pre>
  
  <p><code>./acc2fasta.py 163345 303239</code> ... ...  (up to 110 000).</p>
  
  <p>Actually i use <code>cat acc_file | acc2fasta.py</code>  </p>
  
  <p>Thanks for your help.</p>