old_contents: // Unix environment variables are can be the character set `[a-zA-Z0-9_]` so we
  // need to replace anything that isn't in that to the underscore character. If
  // the variable name starts with a number then prefix it with an underscore.
  
  function shellEscape(name) {
      name = name.replace(/[^a-zA-Z0-9_]/g , '_');
  
      if (name.match(/^[0-9]/)) {
          name = '_' + name;
      }
  
      return name;
  }
  
  // Convert a string to a unix environment variable name by:
  // * Trimming excess space from the provided string and optional stub
  // * Prefixing the string with an optional stub, followed by an underscore
  // * Replacing invalid characters with an underscore
  // * Converting the resultant string to uppercase
  
  function toVariableName(string, stub) {
  
      var name = '';
  
      if (stub !== undefined) {
          name = stub.trim();
      }
  
      if (!name) {
          name = string.trim();
      } else {
          name += '_' + string.trim();
      }
  
      return shellEscape(name).toUpperCase();
  }
  
  module.exports.toVariableName = toVariableName;
  
  
new_contents: // Unix environment variables are can be the character set `[a-zA-Z0-9_]` so we
  // need to replace anything that isn't in that to the underscore character. If
  // the variable name starts with a number then prefix it with an underscore.
  
  function shellEscape(name) {
      name = name.replace(/[^a-zA-Z0-9_]/g , '_');
  
      if (name.match(/^[0-9]/)) {
          name = '_' + name;
      }
  
      return name;
  }
  
  // Convert a string to a unix environment variable name by:
  // * Trimming excess space from the provided string and optional stub
  // * Prefixing the string with an optional stub, followed by an underscore
  // * Replacing invalid characters with an underscore
  // * Converting the resultant string to uppercase
  
  function toVariableName(string, stub) {
  
      var name = '';
  
      if (stub !== undefined) {
          name = stub.trim();
      }
  
      if (!name) {
          name = string.trim();
      } else {
          name += '_' + string.trim();
      }
  
      return shellEscape(name).toUpperCase();
  }
  
  // `getOverride` checks the for an environment variable with the given `name`
  // returning its value if it's set. Numeric values are automatically converted.
  // If no value is found then the given default value will be returned.
  
  function getOverride(name, defaultValue) {
      var value = process.env[name];
      var result = defaultValue;
  
      if (value !== undefined) {
          if (isNaN(+value)) {
              result = value;
          } else {
              result = +value;
          }
      }
  
      return result;
  }
  
  module.exports.toVariableName = toVariableName;
  module.exports.getOverride = getOverride;
  
  
subject: Add method to environment.js to allow retrieval of overrides