/test:
1,2,3
$ fq -d csv . /test
[
  [
    "1",
    "2",
    "3"
  ]
]
$ fq -i
null> "a,b,c,d" | fromcsv | ., tocsv
[
  [
    "a",
    "b",
    "c",
    "d"
  ]
]
"a,b,c,d\n"
null> "a,\"b, c\",d" | fromcsv | ., tocsv
[
  [
    "a",
    "b, c",
    "d"
  ]
]
"a,\"b, c\",d\n"
null> "a\t\"b\t c\"\td" | fromcsv({comma:"\t"}) | ., tocsv({comma: "\t"})
[
  [
    "a",
    "b\t c",
    "d"
  ]
]
"a\t\"b\t c\"\td\n"
null> [[bsl(1;100)]] | tocsv | ., fromcsv
"1267650600228229401496703205376\n"
[
  [
    "1267650600228229401496703205376"
  ]
]
null> ^D