You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: solver.rs
    path of file: ./repos/CreuSAT/CreuSAT/src
    
    the code of the file until where you have to start completion: extern crate creusot_contracts;
use ::std::panic;

use creusot_contracts::{std::*, Ghost, *};

use crate::{
    assignments::*, clause::*, conflict_analysis::*, decision::*, formula::*, trail::*, unit_prop::*, util::*,
    watches::*,
};

// Tmp
#[cfg(creusot)]
use crate::logic::{logic::*, logic_clause::*, logic_formula:
    
pub fn solver(formula: &mut Formula) -> SatResult {
    match formula.check_formula_invariant() {
        SatResult::Unknown => {}
        o => return o,
    }
    let mut trail = Trail::new(formula, Assignments::new(formula));
    let mut decisions = Decisions::new(formula);
    let mut watches = Watches::new(formula);
    watches.init_watches(formula);
    match trail.learn_units(formula, &mut decisions) {
        None => {}
        Some(true) => return SatResult::Unsat,
        Some(false) => return SatResult::Err,
    }
    let mut solver = Solver::new(formula);
    solver.inner(formula, decisions, trail, watches)
}