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: env.rs
    path of file: ./repos/cargo-mobile/src/android
    
    the code of the file until where you have to start completion: use super::{
    ndk,
    source_props::{self, SourceProps},
};
use crate::{
    env::{Env as CoreEnv, Error as CoreError, ExplicitEnv},
    util::cli::{Report, Reportable},
};
use std::path::{Path, PathBuf};
use thiserror::Error;

#[derive(Debug, Error)]
pub enum Error {
    #[error(transparent)]
    CoreEnvError(#[from] CoreError),
    // TODO: we should be nice and provide a platform-specific suggestion
    #[error("Have you installed the Android SDK? The `ANDROID_SDK_ROOT` environment variable isn't set, and is required: {0}")]
    AndroidSdkRootNotSet(#[from] std::env::VarError),
    #[error("Have you installed the Android SDK? The `ANDROID_SDK_ROOT` environment variable is set, but doesn't point to an existing directory.")]
    AndroidSdkRootNotADir,
    #[error(transparent)]
    NdkEnvError(#[from] ndk::Error),
}

impl Reportable for Error {
    fn report(&self) -> Report {
        match self {
            Self::CoreEnvError(err) => err.report(),
            Self::NdkEnvError(err) => err.report(),
            _ => Report::error("Failed to initialize Android environment", self),
        }
    }
}

impl Error {
    pub fn sdk_or_ndk_issue(&se
    
    pub fn from_env(base: CoreEnv) -> Result<Self, Error> {
        let sdk_root = std::env::var("ANDROID_SDK_ROOT")
            .map_err(Error::AndroidSdkRootNotSet)
            .map(PathBuf::from)
            .and_then(|sdk_root| {
                if sdk_root.is_dir() {
                    Ok(sdk_root)
                } else {
                    Err(Error::AndroidSdkRootNotADir)
                }
            })
            .or_else(|err| {
                if let Some(android_home) = std::env::var("ANDROID_HOME")
                    .ok()
                    .map(PathBuf::from)
                    .filter(|android_home| android_home.is_dir())
                {
                    log::warn!("`ANDROID_SDK_ROOT` isn't set; falling back to `ANDROID_HOME`, which is deprecated");
                    Ok(android_home)
                } else {
                    Err(err)
                }
            })
            .or_else(|err| {
                if let Some(android_home) = std::env::var("ANDROID_HOME")
                    .ok()
                    .map(PathBuf::from)
                    .filter(|android_home| android_home.is_dir())
                {
                    log::warn!("`ANDROID_SDK_ROOT` isn't set; falling back to `ANDROID_HOME`, which is deprecated");
                    Ok(android_home)
                } else {
                    Err(err)
                }
            })?;
        Ok(Self {
            base,
            sdk_root,
            ndk: ndk::Env::new()?,
        })
    }