use impl Iterator instead of custom types in `source`
use impl Iterator instead of custom types in `source`

vojtechkral/cargo,rust-lang/cargo,tsurai/cargo,tshepang/cargo,tsurai/cargo,rustyhorde/cargo,vojtechkral/cargo,rustyhorde/cargo,tshepang/cargo,tshepang/cargo,tsurai/cargo,rust-lang/cargo,tsurai/cargo,eminence/cargo,vojtechkral/cargo,eminence/cargo,eminence/cargo,rustyhorde/cargo,rust-lang/cargo,nipunn1313/cargo,eminence/cargo,rustyhorde/cargo,nipunn1313/cargo,tsurai/cargo,rust-lang/cargo,vojtechkral/cargo,tshepang/cargo,nipunn1313/cargo,nipunn1313/cargo