Furthermore, a lack of consensus in the field as to what attributes make a gene truly essential adds another aspect of variation.
She told the Federation that a programme of reform was essential, adding: "If you do not change of your own accord we will impose change on you".
He said the prime minister "thinks that strong and robust investigative journalism is absolutely essential", adding: "He is a strong supporter of the British media's long, proud tradition of that type of journalism".
For me though, its sequel was when the series really became essential, adding much-needed practise and co-op modes.
In a BBC Online review of Gravity, Peter Marsh called it "Absolutely essential", adding that it "manages to be wildly eclectic yet avoids incoherence".
Although high production quality is essential, adding in raw elements such as the low quality phone calls and difficult audio recordings work to draw us deeper into the plot.
Although not essential, adding a couple of pennies to the inside of the bag also seems to help repel flies.
These essentials add up fast.
Amongst essential oils added, basil essential oil could be appropriately used to enhance water vapour barrier property and yielded film with antioxidative activity.
BBC iPlayer An essential add-on for Game Of Thrones viewers struggling with their Greyjoys, Dragonstones or simply who is boffing who.
