write.tree(phy, file = "", append = FALSE,
           digits = 10)"phylo".file = "" (the default) then the
    tree is written on the standard output connection (i.e. the console).TRUE the tree is appended to the file
    without erasing the data possibly existing in the file, otherwise
    the file (if it exists) is overwritten (FALSE the default).file = "", none (invisible
  `NULL') otherwise.  Olsen, G. Interpretation of the "Newick's 8:45" tree format standard.
  
read.tree, read.nexus,
  write.nexus