How would I convert .xml files into .fasta format

Question

I am trying to extract the protein sequence from an .xml file obtained via entrez_fetch for use in a multi sequence analysis, however, this requires the sequence file to be in .fasta format and I am unsure of how to parse this information.

I have used the following code to obtain my .xml file but am unable to use this file in msa package.

#Search NCBI Id
  species <- c("flaviviridae")
  species_ids <- entrez_search(db = "genome", term = species, retmax = 999, use_history = F)
  species_ids$ids

#Fetch protein seq
  search <- entrez_fetch(dbfrom = "genome", db = "protein",  id = species_ids$ids, rettype = "xml", parsed = TRUE)
  search
  
#Parse .xml into .fasta