=== DEPENDENCIES (1 transitive) ===
  conf-pkg-config.4                                  f5167d99d01a
=== STDOUT ===
Processing: [default: loading data]

The following system packages will first need to be installed:
    libffi-dev

<><> Handling external dependencies <><><><><><><><><><><><><><><><><><><><><><>

+ /usr/bin/sudo "apt-get" "install" "-qq" "-yy" "libffi-dev"
- debconf: delaying package configuration, since apt-utils is not installed
- Selecting previously unselected package libffi-dev:amd64.
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- Preparing to unpack .../libffi-dev_3.4.4-1_amd64.deb ...
- Unpacking libffi-dev:amd64 (3.4.4-1) ...
- Setting up libffi-dev:amd64 (3.4.4-1) ...
[conf-libffi: pkg-config libffi]
+ /usr/bin/pkg-config "libffi" (CWD=/home/opam/.opam/default/.opam-switch/build/conf-libffi.2.0.0)
-> compiled  conf-libffi.2.0.0
-> installed conf-libffi.2.0.0

=== STDERR ===