Generic function to convert an object to an object which can be saved as EML
as_eml(x, ...)# S3 method for default
as_eml(x, ...)
A list object which can be converted to EML. It can be
  written to a file using write_eml(). The resulting eml file can be
  validated using eml_validate().
NB: This does only validate the EML format, and NOT the validation as defined in the scheme definition package!
object to be converted.
additional arguments for methods