How to use the cli-ux.default.warn function in cli-ux

case 'at': return [k, v === 'error' ? red(v) : other(v)]
          case 'desc': return [k, red(v)]
          case 'code': return [k, red.bold(v)]
          case 'method': return [k, method(v)]
          case 'dyno': return [k, getColorForIdentifier(v)(v)]
          case 'status': return [k, status(v)]
          case 'path': return [k, path(v)]
          case 'connect': return [k, ms(v)]
          case 'service': return [k, ms(v)]
          default: return [k, other(v)]
        }
      })
      .map(([k, v]) => other(k + '=') + v)
      .join(' ')
  } catch (err) {
    ux.warn(err)
    return body
  }
}

return [
        stateChange[1],
        state(stateChange[2]),
        stateChange[3] || '',
        state(stateChange[4] || '')
      ].join('')
    }
    let exited = body.match(/^(Process exited with status )(\d+)$/)
    if (exited) {
      return [
        exited[1],
        exited[2] === '0' ? c.greenBright(exited[2]) : c.red(exited[2])
      ].join('')
    }
  } catch (err) {
    ux.warn(err)
  }
  return body
}

other(tokens[4]),
        status(tokens[5]),
        other(tokens[6])
      ].join('')
    }
    let route = body.match(/^(.* ")(\w+)(.+)(HTTP\/\d+\.\d+" .*)$/)
    if (route) {
      return [
        route[1],
        method(route[2]),
        path(route[3]),
        route[4]
      ].join('')
    }
  } catch (err) {
    ux.warn(err)
  }
  return body
}

return [
        stateChange[1],
        state(stateChange[2]),
        stateChange[3] || '',
        state(stateChange[4] || '')
      ].join('')
    }
    let exited = body.match(/^(Process exited with status )(\d+)$/)
    if (exited) {
      return [
        exited[1],
        exited[2] === '0' ? c.greenBright(exited[2]) : c.red(exited[2])
      ].join('')
    }
  } catch (err) {
    ux.warn(err)
  }
  return body
}

return parts
      } else if (parts.length === 2) {
        return encodeColor(parts)
      } else {
        return encodeColor([parts[0], parts.splice(1).join("=")])
      }
    })

    return tokens.map(([k, v]) => {
      if (v === undefined) {
        return other(k)
      }
      return other(k + '=') + v
    }).join(' ')
  } catch (err) {
    ux.warn(err)
    return body
  }
}

other(tokens[4]),
        status(tokens[5]),
        other(tokens[6])
      ].join('')
    }
    let route = body.match(/^(.* ")(\w+)(.+)(HTTP\/\d+\.\d+" .*)$/)
    if (route) {
      return [
        route[1],
        method(route[2]),
        path(route[3]),
        route[4]
      ].join('')
    }
  } catch (err) {
    ux.warn(err)
  }
  return body
}