> allRes <- lapply(chrs, workOnChr)
Working on chr1
Error in GenomeInfoDb:::getDanglingSeqlevels(x, new2old = new2old, force = force,  : 
  The following seqlevels are to be dropped but are currently in use (i.e. have ranges on them): chr2, chr3, chr4, chr5, chr6, chr7, chr8,
  chr9, chr10, chr11, chr12, chr13, chr14, chr15, chr16, chr17, chr18, chr19, chr20, chr21, chr22, chrX, chrY. Please use the 'pruning.mode'
  argument to control how to prune 'x', that is, how to remove the ranges in 'x' that are on these sequences. For example, do something like:
  
  seqlevels(x, pruning.mode="coarse") <- new_seqlevels
  
  or
  
  keepSeqlevels(x, new_seqlevels, pruning.mode="coarse")
  
  See ?seqinfo for a description of the pruning modes.