flex.GetChildren undefined

[user747]

go version go1.15.6 linux/amd64

go get -v github.com/esell/twitterMon 
github.com/esell/twitterMon (download)
created GOPATH=/home/x/go; see 'go help gopath'
github.com/ChimeraCoder/anaconda (download)
github.com/gdamore/tcell (download)
github.com/gdamore/encoding (download)
get "golang.org/x/text/encoding": found meta tag get.metaImport{Prefix:"golang.org/x/text", VCS:"git", RepoRoot:"https://go.googlesource.com/text"} at //golang.org/x/text/encoding?go-get=1
get "golang.org/x/text/encoding": verifying non-authoritative meta tag
golang.org/x/text (download)
get "golang.org/x/text/transform": found meta tag get.metaImport{Prefix:"golang.org/x/text", VCS:"git", RepoRoot:"https://go.googlesource.com/text"} at //golang.org/x/text/transform?go-get=1
get "golang.org/x/text/transform": verifying non-authoritative meta tag
github.com/lucasb-eyer/go-colorful (download)
github.com/mattn/go-runewidth (download)
get "golang.org/x/sys/unix": found meta tag get.metaImport{Prefix:"golang.org/x/sys", VCS:"git", RepoRoot:"https://go.googlesource.com/sys"} at //golang.org/x/sys/unix?go-get=1
get "golang.org/x/sys/unix": verifying non-authoritative meta tag
golang.org/x/sys (download)
github.com/mattn/go-sqlite3 (download)
get "gitlab.com/tslocum/cview": found meta tag get.metaImport{Prefix:"gitlab.com/tslocum/cview", VCS:"git", RepoRoot:"https://gitlab.com/tslocum/cview.git"} at //gitlab.com/tslocum/cview?go-get=1
gitlab.com/tslocum/cview (download)
github.com/rivo/uniseg (download)
get "gitlab.com/tslocum/cbind": found meta tag get.metaImport{Prefix:"gitlab.com/tslocum/cbind", VCS:"git", RepoRoot:"https://gitlab.com/tslocum/cbind.git"} at //gitlab.com/tslocum/cbind?go-get=1
gitlab.com/tslocum/cbind (download)
github.com/esell/twitterMon
# github.com/esell/twitterMon
go/src/github.com/esell/twitterMon/gui.go:114:18: flex.GetChildren undefined (type *cview.Flex has no field or method GetChildren)
go/src/github.com/esell/twitterMon/gui.go:137:18: flex.GetChildren undefined (type *cview.Flex has no field or method GetChildren)