query_fetch: Initialize a document fetch query
In hafen/finderquery: Utilities for Building EIOS Finder Queries

Initialize a document fetch query

query_fetch(
  con,
  path = NULL,
  max = 10,
  size = 10000,
  format = c("list", "xml", "file")
)

`con`	A finder connection object from `finder_connect()`.
`path`	An optional directory in which to place downloaded results (required when `format="file"`).
`max`	The maximum number of documents to fetch. Set to <0 to fetch all. When fetching all it is a good idea to first fetch with only a few documents and use `n_docs()` to get a sense of how many will be pulled.
`size`	The number of documents to fetch in each batch (max is 10000).
`format`	One of "list", "xml", "file". In the case of "file", The path to the file will be returned. In all other cases, an object with the fetched data will be returned in the format specified. List results are converted using `xml_to_list()`.